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Subcutaneous Ureteral Bypass (SUB) for Cats
Ureteral obstructions are becoming increasingly common in cats and can lead to serious health issues if left untreated. In a healthy cat, the kidneys filter waste from the blood to produce urine, which travels through the ureters to the bladder and then exits the body via the urethra.
However, some cats are prone to developing calcium oxalate stones, which can partially or completely block the ureters. These blockages can prevent urine from flowing properly, leading to kidney damage over time.
One of the challenges with ureteral obstructions is that symptoms are not always immediately noticeable. Some cats may show signs like reduced appetite, lethargy, or vomiting, but in other cases, the obstruction might go unnoticed until significant damage to the kidney has occurred. This is why early diagnosis is critical to prevent long-term complications.
How are ureteral obstructions diagnosed?
Diagnosing a ureteral obstruction requires a combination of blood and urine tests alongside imaging techniques like X-rays and ultrasound. Calcium oxalate stones are typically visible on X-rays, allowing your vet to pinpoint the exact location of the blockage. Ultrasound is also used to check for kidney enlargement or dilation in the renal pelvis, indicating that the kidney is struggling to pass urine.
In some cases, a dye test may be performed to further confirm the presence of a blockage and assess its severity. Once the obstruction is confirmed, a treatment plan can be created. One of the most effective treatments for ureteral obstructions is placing a Subcutaneous Ureteral Bypass (SUB) device.
What is a subcutaneous ureteral bypass (SUB)?
A SUB device is surgically implanted to help urine bypass the obstruction in the ureter. The device runs from the kidney to the body wall, allowing urine to flow freely without passing through the blocked ureter. This procedure is life-saving, especially in cases where the obstruction is severe and threatens the cat’s kidney function.
However, maintaining an SUB device requires regular flushing to prevent complications like mineral buildup or blood clots. Additionally, feeding your cat a wet diet can help reduce the risk of stone formation by increasing hydration and promoting healthy urine flow.
“A SUB device allows urine to bypass the blocked ureter.”
Monitoring and complications
Although the SUB device is highly effective, it’s not without risks. Cats with pre-existing urinary tract infections are at a higher risk for complications, so regular urine culturing and monitoring are essential to ensure the device continues to function correctly. Occasionally, blood clots can form, requiring a special drug to flush the system.
Despite these risks, the SUB procedure is often the best option for cats with ureteral obstructions. If you suspect your cat shows signs of a blockage, such as difficulty urinating or reduced energy levels, seek vet care as soon as possible. Early intervention can make a significant difference in preserving your cat’s health and well-being.
Are you worried about your cat’s health?
If you are concerned about your cat, please reach out to our friendly team. Call us on 1300 228 377 or fill out the contact form below. In an emergency, please contact your local vet.
For vets – to refer a patient or book a telehealth consultation, please call us on 1300 228 377, book through the portal or fill in the form.
Meet The Author
Dr Rachel Korman
Specialist in Feline Internal Medicine
BVSc MANZCVS (Internal Medicine) FANZCVS (Feline Medicine)
Dr. Korman’s childhood love for cats led her to veterinary medicine, and early on, it was clear that feline care was her calling. After graduating from the University of Queensland in 2000, she worked in small animal and feline-only practices across Australia and the UK.
She received a Senior Clinical Training Scholarship from the Feline Advisory Bureau (now International Cat Care) at the University of Bristol, where she researched feline infectious and haematological diseases, and in 2018, became a Fellow of the Feline Medicine Chapter of the Australian New Zealand College of Veterinary Scientists and a registered Feline Medicine specialist.
Frequently Asked Questions
What is a ureteral obstruction in cats?
A ureteral obstruction occurs when urine cannot flow normally from the kidney to the bladder. This blockage can lead to pressure on the kidney and damage over time.
What causes ureteral obstruction in cats?
Calcium oxalate stones are a common cause of these blockages. They can partially or completely obstruct the ureter and prevent urine flow.
How are ureteral obstructions diagnosed?
Diagnosis usually involves blood and urine testing along with imaging techniques such as X-rays or ultrasound. These tests help locate the obstruction and assess kidney function.
What is a Subcutaneous Ureteral Bypass (SUB) device?
A SUB device is surgically implanted to bypass the blocked ureter. It redirects urine flow from the kidney directly to the bladder.
Why is early treatment important for ureteral obstruction?
If untreated, the obstruction can lead to worsening kidney damage. Early diagnosis and treatment help protect kidney function
Patient Stories
Our commitment to feline health is best seen in the stories of the cats we’ve had the privilege of treating. These journeys highlight the dedication, expertise and compassion that drive us.
Each patient faced unique challenges, and it was our honour to offer high-quality care and help them regain strength and happiness. We value the deep bonds with cats and their owners, knowing the difference we make in their lives.
Kitty, a lymphoma survivor
We first met Kitty after she was referred to CSS for the evaluation of a large intestinal mass
Poppi finds her feet again
Following surgery to remove a hairball obstruction, Poppi was referred to us at CSS as she had not bounced back as expected
Rusty and his ongoing chronic rhinitis journey
Lifelong nasal issues, including persistent discharge and breathing noise, have been a bit of a thorn in Rusty’s side.
Lando’s long game with cryptococcus
Lando was referred to CSS because he had a swelling under his jaw that wouldn’t go away.
Popeye coughs up the culprit
Ares is a handsome young Maine Coon who was referred to CSS after presenting at AES with sudden lameness in his back leg.
Key Takeaways
Ureteral obstruction occurs when urine cannot pass normally from the kidney to the bladder.
Calcium oxalate stones are a common cause of ureteral blockages in cats.
A Subcutaneous Ureteral Bypass (SUB) device can help urine bypass the blockage and restore normal flow.
Cat Specialist Services Reviews 
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Tanya Bell
6 months ago
We transported our cat here from another animal hospital, as his condition was too complex for them. Our pet was given the highest quality of care, multiple investigations/procedures being able to be done at the one place a godsend. We were kept up to date frequently throughout his stay. All questions & options explained thoroughly. Being able to have private visits certainly helped us and our cat too. I would highly recommend Cat Specialist Services at Underwood. Amazing staff from reception, vet nurses, vets & specialists. Oh, and yes he is recovering wonderfully at home.
Melinda Cox
A month ago
So very happy we were asked to come here for advice for our NORBIT. He has had 2 x UTI blockages within weeks of each other since turning 6. Surgery seemed to be his only option and he didn’t feel it was very fair on him if we didn’t at least exhaust all other avenues first.
Dr Allison was very thorough in her tests and has let us know she would like to treat the cause of the problem. Great news.
It may lead to removal of crystals in his bladder if his diet doesn’t let him pass them naturally.
At least this surgery won’t be as severe at taking his penis off him – so as his fur parents – we are very happy with this.
We await further tests to see what’s in store for him.
NORBIT will now be a patient of the clinic as we are so far very happy with his treatment thus far.
Lesley Rosekrans
A month ago
Hi has only been a week since losing my beautiful Peaches but can’t thank Dr Cindy, Maree and Jackie enough for the tender care they gave her and they after care they gave me. I sincerely thank them and can’t recommend the Clinic highly enough they are such caring people. Peaches I’m happier times.
Madison McEwan
A month ago
I cannot thank the entire CSS team enough and especially Dr Cindy for the care they provided for our boy with a urinary blockage, and we will be taking both our cats here from now on. The clinic is exceptionally clean and calming compared to all other clinics we’ve been too, and all staff from the reception to the nurses/vets were so supportive during a stressful time. I knew from the first minute that I got to see him after he was transferred that he was in the best place, and that the staff genuinely care about their well-being and positive long term outcomes. We were given regular updates and full transparency, so much information including QR video codes on how to administer medications, along with print outs and emails about how to best help avoid future issues or recurrence. Our boy got to smooch on everyone and was beyond well looked after. Thank you again, you all made an incredibly stressful situation actually manageable and calming.
Astrid El Gamal
6 months ago
Dr Wan-Ju has been treating my baby since her first seizure in November 2025 and she has been fantastic.
Everybody at the clinic is so friendly and caring and I know my baby is in good hands.
Thank you team!
Deeba M
3 months ago
Dr Alison Jukes from CSS Underwood is an AMAZING feline physician. She is kind, professional, thorough and our cat is blessed to have her on his side. She even was able to save us money and invasiveness by being skilled to the level of doing ultrasound on two separate occasions without our cat needing to go under full sedation. Our other cat was recently seen by Dr Jukes as well, and she made sure our cat’s heart was ok. I also want to thank the lovely Jacqueline and Mairead from customer care. They are very kind each time I see them and call up. Sending thanks from our family, including Smokey and Floozy!
Judith Dionysius
A month ago
My whole experience with CSS was positive – from the first email I received giving lots of information regarding the process of radioactive iodine treatment to the expected costs, to checking my cat in for the treatment, boarding for 2 weeks after the treatment and picking her up to come home. They didn’t push for any tests that were not necessary.
Janelle Wieden
5 months ago
We never knew this service existed but we are very grateful we were referred to them. Our vet Cindy was really great, she made us feel at ease during a very stressful time. We got the sense straight away the Leo was in good hands. This service made us feel better knowing that they specialise is cats only. Would highly recommend their services
Georgia Carter
5 months ago
My Lani finished her I-131 treatment today and I am beyond impressed with the way she was looked after. I am by definition a neurotic pet owner and sending my fur child away for a week was seriously daunting.
I was given daily updates about how kitty was eating, toileting and behaving. This really put my mind at ease. Vets and vet nurses were so accomodating and allowed Lani to have her favourite foods from home prepared her favourite way.
Her vet was so thorough when explaining her treatment and condition to me.
The ladies at reception were so friendly and understanding.
I honestly cannot recommend this clinic enough and I am so thankful for the positive experience Lani and I have had.
Lauren Woodward
A year ago
My sweet ginger boy Louis was hospitalised at CSS for a Urinary Obstruction. Dr Cindy and all the reception staff were amazing and empathetic. I would often ring up with questions post procedure and Dr Cindy would make time to talk and explain things to me
Service Locations
Cat Specialists accepts referrals for cats across Brisbane and surrounding regions, working closely with local veterinary clinics to provide specialist diagnosis, treatment, and ongoing management.
Contacting Us
Pet Owners
If you would like to talk about treatment for your cat, call us on 1300 228 377 or fill in the form.
In an emergency, please contact your local vet.
Vets and Nurses
To refer a patient or book a telehealth consultation please call us on 1300 228 377, book through the portal or fill in the form. For advice calls, please see the guidelines here.
Monday-Friday: 8 am-6 pmSaturday/Sunday - Closed